Field of the Disclosure
The present disclosure relates to a method and device for bioengineering a targeted bone tissue and modulating the homeostasis of osteogenesis and bone resorption by a localized delivery of peripheral blood mononuclear cells and/or hematopoietic stem cells, and/or cells, such as osteoclasts, obtained by the ex vivo differentiation of these cells.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
Pathological bone conditions are generally classified as belonging to either one of two broad categories comprising excessive bone loss, or excessive bone gain. The mechanism of either excessive bone loss or gain is believed to involve imbalances in the process of bone remodeling. Bone remodeling occurs throughout the lifespan, and involves the erosion and filling of discrete sites on the surfaces of the bones by an organized group of cells. These ‘basic multicellular units’ as they are known, comprise a group of cells that first dissolve an area of the bone surface and, subsequently, fill it in with new bone. The units consist primarily of osteoclasts, osteoblasts, and their cellular precursors including, but not limited to, monocytes derived from hematopoietic stem cells. In the remodeling cycle, bone is resorbed at the site of an activated unit by osteoclasts, forming a resorption cavity. This cavity is then filled with bone by osteoblasts. Certain factors can delay, prevent, and even reverse, the ossification of bone. This can be accomplished by a decrease in both the number and activation of osteoblasts, as well as an increase in the number and activity of osteoclasts.
Osteoclasts, as members of the ‘basic multicellular units’, are multinucleated cells that resorb bone tissue. Orthopedic and orthodontic literature confirms that osteoclasts are a key factor in the bone remodeling mechanism. [Miyamoto, T. and T. Suda, Differentiation and function of osteoclasts. Keio J Med, 2003 52(1): p. 1-7. Incorporated herein by reference in its entirety.] Osteoclasts are not simply bone resorbing cells; they also regulate osteoblast function both positively and negatively. [Tatsumi, S., et al., Targeted ablation of osteocytes induces osteoporosis with defective mechanotransduction. Cell Metab, 2007. 5(6): p. 464-75. Incorporated herein by reference in its entirety.] Activation of osteoclasts is generally thought to involve the release of organic acids and membrane-bound enzyme packages onto the surface of the bone. The products of resorption are then taken up via endocytosis for additional intracellular processing within cytoplasmic vacuoles.
Osteoclast-released enzymes involved with the bone remodeling and resorption process are collagenolytic, papain-like cysteine proteases. These include Cathepsin B, C, D, E, G, K and L. Cathepsin K, with optimal enzymatic activity in acidic conditions, is considered the major cathepsin protease involved in the degradation of type I collagen, elastin, and other non-collagenous proteins. Cathepsin K expression is stimulated by inflammatory cytokines that are released after tissue injury. Another osteoclast-released enzyme that appears to be involved in bone matrix degradation is tartrate-resistant acid phosphatase (TRAP). TRAP can dephosphorylate the protein osteopontin, which has been revealed as a key player in anchoring osteoclasts to the mineral matrix of bones. [Reinholt F P, Hultenby K, Oldberg A, Heinegård D (June 1990). “Osteopontin—a possible anchor of osteoclasts to bone”. Proc. Natl. Acad. Sci. U.S.A. 87 (12): 4473-5. Incorporated herein by reference in its entirety.]
Additionally, hematopoietic stem cells (HSCs) appear to play a greater role in bone maintenance than previously thought. The HSC niche, a particular microenvironment in the bone marrow cavity, has been identified as the controller of a HSC's fate. Notably, active osteoclasts, in addition to osteoblasts, are reasoned to take part in the maintenance of the HSC niche. It is postulated that if the threshold for the minimum required bone marrow cavity space to maintain HSC numbers is exceeded, a reduction in the number of HSC will occur. Osteoclastic bone resorption retracts old osteoblasts from the remodeling endosteal surface and recruits new active matrix producing osteoblasts to the eroded bone surface. Thus inhibition of osteoclast function reduces the rate of osteoblast turnover and may consequently reduce the formation of niche-osteoblasts. A decrease in the number of osteoclasts, or an inhibition of osteoclast function, may result in a reduced number of hematopoietic stem cells (HSCs). [Lymperi S, Ersek A, Ferraro F, Dazzi F, Horwood N, ‘Inhibition of osteoclast function reduces hematopoietic stem cell numbers in vivo’ (published online Dec. 3, 2010 ahead of print) Blood doi: 10.1182/blood-2010-05-282855. Incorporated herein by reference in its entirety.] Also, hematopoietic stem cells (HSC) are known to differentiate into monoblasts that can further differentiate into monocytes. In turn, monocytes can differentiate into a variety of cells including, but not limited to, osteoclasts. It is therefore desirable to have HSCs present in an area that requires osteoclasts, so as to assist in healing a bone wound site that may be cell-poor.
Failure in the production, or metabolic activity, of osteoclasts, mononuclear cells, and/or hematopoietic can lead to a variety of detrimental conditions, as these cells play a significant role in osteogenesis and bone resorption. Bone formation conditions and/or bone disorders linked to an abnormal deposition and/or abnormal turn-over of bone tissues include, but are not limited to, craniosynostosis, hallux abductovalgus abnormalities, osteogenic sarcoma (Osteosarcoma), osteocartilaginous exostosis, ankylosis, osteopetrosis, and osteonecrosis, are briefly outlined below.
Osteopetrosis: This bone condition is known to cause the deformation of the skull and jaw, immature fusion at craniofacial sutures, and failure of tooth eruption. [Kawata, T., et al., Midpalatal suture of osteopetrotic (op/op) mice exhibits immature fusion. Exp Anim, 1998. 47(4): p. 277-81. Incorporated herein by reference in its entirety.] The clinical syndrome osteopetrosis is characterized by the failure of osteoclasts to resorb bone; resulting in systemic bone sclerosis. Three distinctive clinical forms of the genetically inherited disease—infantile, intermediate, and adult onset—are identified based on age and clinical features. As a consequence of this condition, bone modeling and remodeling are impaired, leading to serious skeletal issues. Unexpectedly, skeletal fragility occurs in spite of the increased bone mass associated with osteopetrosis. Clinically, mutations in the cathepsin K gene are believed responsible for pycnodysostosis, a hereditary osteopetrotic disease, characterised by a lack of functional cathepsin K expression. Various treatment protocols have been developed to treat osteopetrosis, for example hematopoietic stem cell and bone marrow systemic transplantation, which is also a prerequisite for normal dental development and eruption of teeth in patients with osteopetrosis. [Jalevik, B., A. Fasth, and G. Dahllof, Dental development after successful treatment of infantile osteopetrosis with bone marrow transplantation. Bone Marrow Transplant, 2002. 29(6): p. 537-40, Steward, C. G., Hematopoietic stem cell transplantation for osteopetrosis. Pediatr Clin North Am, 2010. 57(1): p. 171-80. Incorporated herein by reference in their entirety.]
Craniosynostosis: This bone condition involves the premature ossification of cranial sutures. The term sutures refer to the fibrous joints between the bones in the skull, however sutures are also active growth sites that influence the development, growth and shaping of the face and cranium. Occurring in approximately one of every 2,000 live births, craniosynostosis is characterized by the premature fusion of one or more cranial and/or facial sutures before the brain growth is complete. This premature fusion can cause increased intracranial pressure, resulting in possible impairment of both visual and neurocognitive skills if left untreated. Complex craniosynostosis, involving more than one suture, occurs in approximately 5% to 15% of the cases. At the present time, the only therapeutic measure for craniosynostosis is surgical correction by cranial vault reconstruction. This highly invasive and traumatic procedure involves the reshaping of skull bones and the removal of synostosed bone.
Bunions: Bone disorders or conditions of the first metatarsophalangeal joint encompass a variety of abnormalities. These include hallux abductovalgus abnormalities, otherwise known as bunions. Bunions are boney growths or enlargements of the joint typically found below the toes. While bunions can theoretically occur in any toe, they typically occur in the big toe, (hallux valgus) and occasionally in the little toe. Almost all bunions are related to a combination of a faulty gait, worsened by ill-fitting shoes. The results are an enlargement and deformation of the first metatarsophalangeal joint, which grows new bone tissue to help balance the gait. Once a bunion has formed, the mechanics of the foot and toes are further altered, exacerbating the problem. As a result, pain severe enough to warrant surgery may occur in order to remove the abnormal bony enlargement. This is a costly and painful procedure in which a patient can expect a 6-8 week recovery period.
Osteosarcoma: This is the most common histological form of primary bone cancer. Specifically, it is an aggressive malignant neoplasm which arises from primitive transformed cells of mesenchymal origin that exhibits osteoblastic differentiation and produces malignant osteoid. It is most prevalent in children and young adults. Treatment normally involves a combination of chemotherapy and surgery.
“Cartilaginous exostosis” or “Osteocartilaginous exostosis”: These terms are considered by some sources to be synonymous with Osteochondroma, but this interpretation is not universal. An exostosis (plural: exostoses) is the formation of new bone on the surface of a bone, due to excess calcium deposits. Exostoses can cause chronic mild to severe pain depending on the shape, size, and location of the lesion. It is most commonly found in places like the ribs, where small bone growths form, but sometimes larger growths can grow on places like the ankles, knees, shoulders, elbows and hips. Very rarely are they on the skull. They normally form on the joints of bones, and can grow upwards. For example, if an extra bone formed on the ankle, it might grow up to the shin. Complications seen with an exostosis can include fracture, vascular injury, bursa formation, neurologic compromise, and malignant transformation. Treatment for these complications, as well as treatment for those exostoses that are painful or aesthetically unpleasing, is surgery.
Ankylosis: Ankylosis in medical terms is the stiffening or immobility of a joint resulting from disease, trauma, surgery, or bone fusion. Ankylosis occurring in a joint can result in abnormal adhesion and rigidity of the bones of the joint, so that no motion can take place between them. Excision of an ankylosed joint, or area of ankylosed bone, may restore free mobility and usefulness to the corresponding limb.
Ectopic Mineralization: Ectopic mineralization, or etopic calcification, make up a distinct category of abnormal calcium deposition which involves the pathologic deposition of calcium salts in tissues. This can furthermore result in the formation of osseous tissue in such soft tissues as the lungs, eyes, arteries, breast, ovaries, uterus, kidneys and cardiovascular tissues. Cardiovascular concerns include cardiac valve mineralization of both biological and prosthetic heart valves. Treatments for ectopic mineralization conditions are varied.
Osteonecrosis (ON) and Osteonecrosis of the Jaw (ONJ): Osteonecrosis is characterized by the appearance of dead (necrotic) bone forming in various bones of the body. Bones such as the femoral head, and the mandible and/or maxilla of the jaw are common sites for osteonecrosis, and osteonecrosis of the jaw respectively. In many cases, pain and edema of the surrounding tissues accompanies or precedes the development of the necrotic bone. Some forms of ON and ONJ are believed to develop due to a decrease in blood flow to the bone which can occur as a result of a traumatic event, however, there are cases of ON and ONJ which arise due to non-traumatic factors. A percentage of these cases may be termed medication-related osteonecrosis, and are brought about in part by prescription drug use. Medications currently believed to play a role in the development of ON and ONJ include those such as, but not limited to, bisphosphonates, zoledronate, and denosumab. Currently, the pathophysiology of all forms of osteonecrosis and osteonecrosis of the jaw is unknown, although it is believed that many factors contribute to its development. These factors include a compromised immune system, age, corticosteroid use, tissue trauma, Vitamin D deficiency, and the aforementioned medication use. However, how these factors might initially contribute to the development of ON and ONJ is currently unknown, and a topic of great interest. Currently, there are no products available to prevent ON and ONJ. Existing treatments for ON and ONJ are palliative and consist of various protocols which may include a surgical debridement of the necrotic bone—with very limited extension to viable bleeding bone, coupled with analgesic, chlorhexidine rinses and antibiotics. With the majority of minor surgical debridement situations, any tissue death will be repaired by the body. However, with more invasive debridement surgeries comes the undesirable possibility of developing what is termed a ‘critical size defect’. The classical definition of a critical size defect is, ‘the smallest size tissue defect that will not completely heal over the natural lifetime of an animal’. With regard to bone tissue, any orthotopic defect that the body cannot heal itself, i.e. without medical intervention, is known as a critical size defect. As such, materials or strategies that can cause a complete regeneration of the bone tissue in these defects are highly desired. These may include materials that are considered capable of generating bone at a site and time when bone would otherwise not be present. In many cases, a cosmetic restoration of the area of bone loss with materials considered to bridge non-union defects has been the only available option of treatment to date.
Osteoradionecrosis (ORN): Osteoradionecrosis of the jaw (ORNJ) occurs in subjects receiving radiation treatment, for example, during cancer therapy. It is caused by the radiation that jaw tumor(s) are treated with to eradicate the tumor(s). ORNJ may be managed by increasing local vascularity, and hyperbaric oxygen (HBO) treatment may be an effective option for treating ORNJ by seemingly increasing the formation of new blood vessels.
Further to the function of osteoclasts in bone disorders or conditions, is the role that osteoclasts play in accelerating the rate of tooth movement during orthodontic treatment. Many individuals seek orthodontic treatment to position their teeth where function and/or aesthetics are greatly improved. In order to achieve the desired tooth alignment, bone remolding is necessary, as it is the basis for all orthodontic tooth movement. [Henneman, S., J. W. Von den Hoff, and J. C. Maltha, Mechanobiology of tooth movement. Eur J Orthod, 2008. 30(3): p. 299-306., Xie, R., A. M. Kuijpers-Jagtman, and J. C. Maltha, Osteoclast differentiation during experimental tooth movement by a short-term force application: an immunohistochemical study in rats. Acta Odontol Scand, 2008. 66(5): p. 314-20. Incorporated herein by reference in their entirety.] Conventionally, appliances such as braces have been applied to a patient's teeth by an orthodontist or dentist. The appliance then exerts a continual force on the teeth so as to gradually urge them toward their intended positions. Over time, and with a series of clinical visits to make adjustments to the appliance, the teeth attain their desired alignment.
Primarily, any osteoclast activation during orthodontic treatment is dependent on the orthodontic forces. This activation requires frequent office visits to initially recruit and then sustain a biologically active level of osteoclasts through the application of force placed upon the teeth. Maintaining an elevated concentration of osteoclasts is an important factor in facilitating and accelerating the rate of tooth movement. [Xie, R., A. M. Kuijpers-Jagtman, and J. C. Maltha, Osteoclast differentiation during experimental tooth movement by a short-term force application: an immunohistochemical study in rats. Acta Odontol Scand, 2008. 66(5): p. 314-20. Incorporated herein by reference in its entirety.]
During treatment, orthopedic and orthodontic forces are used as mechanical stimulus to activate the biological response and increase osteoclast activity. The application of additional forces beyond the optimal force magnitude to increase the biological response can lead to a significant injury to the teeth and surrounding tissues either with or without an increase in the biological response. [Yee, J. A., et al., Rate of tooth movement under heavy and light continuous orthodontic forces. Am J Orthod Dentofacial Orthop, 2009. 136(2): p. 150 e1-9; discussion 150-1. Yee, J. A., et al., Rate of tooth movement under heavy and light continuous orthodontic forces. Am J Orthod Dentofacial Orthop, 2009. 136(2): p. 150 e1-9; discussion 150-1. Incorporated herein by reference in their entirety.]. One of the main factors that controls tooth eruption is the activity of osteoclasts, which can delay or accelerate this process.
Further to this process, if a subject is undergoing dentofacial orthopedic treatment, tensile stresses are often employed along a suture to stimulate the growth of different areas in the maxilla, such as the mid palatal suture. The mechanism of this treatment is also stimulated by early osteoclast activation, followed by bone formation.
Although these methods facilitate and accelerate the rate of tooth movement, they still do not meet all of the clinical needs. The limited clinical outcome of these methods may be due in part to the fact that they target osteoclasts indirectly in order to stimulate the biological response, and this is very difficult to achieve.
In orthodontic clinics, patients may begin Phase 1 treatment as early as ages five or six years in order to treat dentofacial bone conditions, otherwise known by the medical term ‘malocclusion’. Examples of malocclusions include, but are not limited to, crooked teeth, overbites, and under-bites. The first phase, early treatment, is designed to enable correct biting and chewing, along with guiding the growth of the jaw bones that support the teeth. This is done so as to direct the teeth to come in straight and to direct the jaw bone to grow in the correct alignment. Early treatment also lowers the risk of damage or breakage to protruding, or misaligned, front teeth. Treatment then resumes as a Phase 2 treatment once the patient experiences the eruption of all permanent teeth.
The second phase, traditional braces, is designed to move permanent teeth into their final positions and continue improving tooth function and facial appearance. Both phases can last several years, with treatment time ranging up to ten years in duration.
During the mixed dentition phase of a child, an orthodontist watches for any potential problems with the eruption of the teeth. A delay in the eruption of primary and permanent teeth occurs when a tooth, or teeth, stop erupting and stay in the same place, causing the permanent tooth or teeth to be displaced upon emergence. The delay of the eruption of primary and permanent teeth can have an effect on the growth and development of the jaws and the developing occlusion. Crowding, distortion of the alveolar jaw bone, space loss and distortion of jaw height are some conditions caused by un-erupted teeth.
In other situations, children may experience delays in desired tooth eruption due to the premature loss of deciduous teeth by injury, decay, or any number of underlying genetic causes. For those young subjects who lose baby teeth early, it is desirable to speed up the emergence of the permanent, or adult, teeth so as to provide the child with not only an aesthetically pleasing smile, but a chewing surface which will also serve to prevent any additional tooth loss due to contact withdrawal. Therefore, in treating a delay in tooth eruption it is desirable to target any critical problem first, and to then accelerate the emergence of the adult teeth so as to avoid additional tooth loss in these subjects. With the first phase of orthodontic care involving treating the jaw so as to correct for biting and chewing, commencement of the second phase may be separated by a long period of time while the subject awaits the emergence of their adult teeth. If the length of time from loss of deciduous teeth to emergence of adult teeth is shortened, the second phase treatment could commence in a much more timely manner, thus saving time, and potentially, monetary costs. Therefore, clinical methods that can locally target tooth eruption and increase the speed of treatment (in years) so as to facilitate the progression of this process are desired.
In light of the invasive and traumatic surgical treatments currently used for bone disorders and conditions such as osteonecrosis and osteonecrosis of the jaw, as well as etopic mineralization conditions, and the shortcomings of the orthodontic field in the clinical treatment of dentofacial conditions, it is necessary to find minimally invasive approaches for the treatment of such.